Refactor Tab view, point ROOT to tab content, add support for dropdown tabs

[abalakh]

Currently Tab's ROOT points to tab link, not to tab content, making it impossible to use relative locators for tab content:

ROOT = ParametrizedLocator(
        './/ul[contains(@class, "nav-tabs")]/li[normalize-space(.)={@tab_name|quote}]')

Also in foreman there're tabs which are included in some parent dropdown menu:

[abalakh]

I've fixed it in following way for foreman, but can't guarantee it won't introduce any regressions to cfme

class Tab(View):
    """Represents the Tab view.

    Selects itself automatically when any child widget gets accessed, ensuring
    that the widget is visible.
    """
    TAB_NAME = None
    PARENT_TAB_NAME = None

    ROOT = ParametrizedLocator('.//div[contains(@class, "page-content")]')
    TAB = ParametrizedLocator(
        './../preceding-sibling::div//ul[contains(@class, "nav-tabs")]'
        '/li[a[normalize-space(.)={@tab_name|quote}]]')
    PARENT_TAB = ParametrizedLocator(
        './..//preceding-sibling::div//ul[contains(@class, "nav-tabs")]'
        '/li[a[normalize-space(.)={@parent_tab_name|quote}]]')
    CHILD_TAB = ParametrizedLocator(
        './../preceding-sibling::div//ul[contains(@class, "nav-tabs")]'
        '/li/a[normalize-space(.)={@parent_tab_name|quote}]/ul'
        '/li[normalize-space(.)={@tab_name|quote}]')

    @property
    def tab_name(self):
        return self.TAB_NAME or type(self).__name__.capitalize()

    def is_active(self):
        return 'active' in self.browser.classes(self.TAB)

    def is_disabled(self):
        return 'disabled' in self.browser.classes(self.TAB)

    def select(self):
        if not self.is_active():
            if self.is_disabled():
                raise ValueError(
                    'The tab {} you are trying to select is disabled'
                    .format(self.tab_name)
                )
            self.logger.info('Opening the tab %s', self.tab_name)
            if not self.PARENT_TAB_NAME:
                self.browser.click(self.TAB)
            else:
                self.browser.click(self.PARENT_TAB)
                self.browser.click(self.CHILD_TAB)

    def child_widget_accessed(self, widget):
        # Select the tab
        self.select()

    def __repr__(self):
        return '<Tab {!r}>'.format(self.tab_name)

[psav]

So we can definitely take a look if Tab can be used generically, alternatively we can have a separate widget for tab with dropdown. @mfalesni can you please take a look at this.

[mfalesni]

This solution is quite specific. I want to try and remove ROOT from the Tab, then you can import Tab and subclass it and add the modifications in your project.

[mfalesni]

I created #50 where I am trying to remove the ROOT from the Tab so teams can specify their own.

[abalakh]

@mfalesni and what about dropdowns support? That's not something specific to foreman/katello, they are officially supported by patternfly: https://www.patternfly.org/pattern-library/widgets/#tabs

[mfalesni]

I think I will make that an inherited widget.